Resolve a TODO of BucketAllocator: "Why we add the extra 1024 bytes? Slop?"

// TODO: Why we add the extra 1024 bytes? Slop?
private static final int DEFAULT_BUCKET_SIZES[] = { 4 * 1024 + 1024, 8 * 1024 + 1024,
 16 * 1024 + 1024, 32 * 1024 + 1024, 40 * 1024 + 1024, 48 * 1024 + 1024,
 56 * 1024 + 1024, 64 * 1024 + 1024, 96 * 1024 + 1024, 128 * 1024 + 1024,
 192 * 1024 + 1024, 256 * 1024 + 1024, 384 * 1024 + 1024,
 512 * 1024 + 1024 };